Apparatus for recovering material used in gravity separation



Feb. 27, 1934. Du FONT 1,949,117

APPARATUS FOR RECOVERING MATERIAL USED IN GRAVITY SEPARATION Filed June 27, 1930 Patented Feb. 27, 1934 UNITED STATES PATENT DFFICE APPARATUS FOR RECOVERING MATERIAL USED IN GRAVITY SEPARATION Francis I. du Pont, Wilmington, Del. Application June 27, 1930. Serial No. 464,248

1 Claim.

My invention relates to an apparatus for recovering material used in gravity separation.

While I contemplate my invention as advan tageous in connection with various methods for l efiecting gravity separation, it will be found of special advantage in connection with the recovery of material used in effecting gravity separation of coal from impurities, as slate and the like, in accordance with, for example, the method described and claimed in an application for patent filed by me January 28, 1930, Serial No. 423,925, and with reference to which for illustrative purposes, I will describe my present invention.

In my application for patent referred to above, I have disclosed and claimed a process involving the use of sodium thiosulphate in connection with the separation of coal from impurities, such as slate and the like. The process described and claimed involves the introduction of coal and its impurities into a bath of sodium triosulphate in which gravity separation occurs, the coal floating in the bath and the impurities sinking, and from which the coal and impurities are separately removed.

As is well known the coal and impurities removed from the bath carry a substantial amount or sodium thiosulphate, which, unless recovered, will be lost and will increase the expense of 3 efiecting the separation.

Now, it is the object of my invention to provide an apparatus for effecting recovery of the sodium thiosulphate carried out of the bath with the separated materials, and which will be emcient and at the same time simple and economic of construction.

In proceeding in accordance with the method, the material, as for example goal, on removal from the bath and carrying sodium thiosulphate 10 is passed in counterflow relative to a washing medium, as water. The material is divided into batches in containers and fresh water is introduced at the top of one container and permitted to flow from the bottom thereof into I another, at a lower level, and so on through a series. The flow from container to container is from a point such as to maintain a level of water in each container above the level of coal therein.

In carrying out the method, the batch into which the fresh water is introduced has pre viously been washed a plurality of times with water received from previous batches. Thus, the coal carrying the highest concentration of sodium thiosulphate is first washed with water carrying the highest concentration of the salt and the concentration of salt in the wash water and the amount of salt carried by the coal decreases through successive batches to that into which fresh water is introduced.

Further, due to the maintenance of water in each container at a level above the coal therein the passage or flow of the water through the coal will proceed in a particularly orderly manner owing to the increase in gravity of the water due to the salt dissolved from the coal, and which will prevent a mixing of wash water at any point in a container with wash water at a higher point. Thus, the amount of salt carried by the coal and the concentration of salt in the wash water and hence its gravity will vary from top to bottom of each container. 7

Thus, in accordance with the method, the wash water will continuously increase in concentration of salt, and hence in gravity, in the direction of its flow, and will to a minimum extent, at any point in its passage in contact with the coal, mix with wash water of lower concentration or gravity. Thus the coal will be continuously freed from salt.

It is believed that the practical carrying out of the method will be made entirely clear from the following description of the construction and operation of the apparatus, exemplifying an embodiment of my invention, illustrated in the accompanying drawing, in which:

The single figure is a side view, partly in section, of an apparatus embodying my invention.

In the drawing A, A indicate suitable supports for a pair of rails, one of which is indicated by the letter B. The rails B extend on a substantial slope from the support A to the support A, which is made higher than the support A, and extend beyond the supports to convenient loading and discharging points for cars or containers C, provided with flanged wheels (1, and adapted to travel on the rails.

Each of the cars 0 is desirably of substantial depth and is provided with a perforated false bottom I positioned above the true bottom which is sloped, as shown at g, to form a sump beneath the false bottom upon which a batch of material h to be washed is supported.

Extending upwardly from the lower portion or the sump formed beneath the false bottom f is a pipe 1', the upper end of which is slightly below the top of the car and is bent over as indicated at ;i to discharge wash water from the sump into the top of an adjacent car.

Adjacent to the support A is provided a water supply pipe e positioned to discharge into the top of a car C positioned at the top of the sloping portion of the rails B, and a drain is is provided adjacent to support A and positioned to receive water and salt, washed from the material in cars C and discharged through pipe i from a car 0 positioned at the lower end of the sloping portion of the rails B.

The practical carrying out of the method will be understood in connection with a description of the application of the above described apparatus to, for illustrative purposes, the washing of coal which has been separated from impurities, as slate, shale, etc. through the medium of a bath of sodium thiosulphate.

The coal withdrawn by means of suitable apparatus from a bath and carrying sodium thiosulphate is discharged or otherwise placed in cars C which are advanced on and up the sloping portion of rails B and beyond to a point of discharge from which they are returned to be refilled. The filled cars are advanced in close proximity up the sloping portion of the rails B and in a step by step manner so that the car a: at the top of the slope will receive water from the pipe e to a level above the coal and the water as it dissolves salt will gravitate down through the coal in the car a: and flow through the pipe i into the top of the next adjacent car below to dissolve more salt, become of higher gravity and gravitate down through the coal therein and so on from car to car down the slope. When the washing is initially started the cars are permitted to remain on the slope until water has flowed from the car I to the car 1/ at the bottom of the slope and all the cars are filled with water to a level above the coal, after which they are advanced a distance of one car periodically after a suflicient quantity of water is introduced into car a: and flow from car to car has occurred.

The wash water flowing from pipe 1' of the lowest car 1 will flow into the drain it, by which it will be led to, for example, an evaporator in which the water will be evaporated, and the salt recovered for reuse.

It will now be noted that the wash water of increasing concentration of salt is counterflowed relative to the batches of coal in the several cars and which carry increasing amounts of salt, i. e. the coal in car a, washed with fresh water, carries a relatively small amount of salt since it has been washed a plurality of times, while the coal in car 1/, washed with water which has passed through a plurality of cars, carries a relatively large amount of salt since it is unwashed.

Further, it will be noted that the gravity of the wash water constantly increases as it dissolves salt from the coal in successive cars and that hence, due to increase in gravity from dissolved salt the water gravitates through the several batches of coal and the water of maximum gravity passes from one batch to the next without mixing with the water of lower gravity introduced into the batches respectively.

It will be understood that while I have more particularly described my invention in connection with the recovery of sodium thiosulphate from coal separated from impurities thereby, I contemplate its use in the recovery of any soluble material adapted to be dissolved by a suitable solvent from a substance by which it is carried and which will increase the gravity of the washing medium, as for example, a soluble salt.

What I claim and desire to protect by Letters Patent is:

Apparatus for the recovery of material from a solid which includes a sloping support, a plurality of independent containers for batches of the substance arranged in a series on said support, means for introducing liquid into the container at the highest level on said support, means for supporting the batches in spaced relation from the bottom of each container, and means for guiding liquid from beneath the batch of each container into the next lower container, said support including upper and lower extensions for placement and removal of containers.

FRANCIS I. DU PONT. 

